CN112585023A

CN112585023A - Powertrain system, vehicle and method for executing gear shifting in powertrain system

Info

Publication number: CN112585023A
Application number: CN201980053868.9A
Authority: CN
Inventors: 吉尔·布鲁德里
Original assignee: Buludili Green Transportation Co ltd
Current assignee: Buludili Green Transportation Co ltd
Priority date: 2018-08-15
Filing date: 2019-08-15
Publication date: 2021-03-30
Anticipated expiration: 2039-08-15
Also published as: US11554659B2; US20210309095A1; WO2020035558A1; CN117962589A; EP4173866A3; EP3837129A1; EP3837129B1; EP4173866B1; NO20181078A1; CN112585023B; EP4173866A2; NO346107B1

Abstract

The invention provides a power system comprising a transmission (2), a first electric motor (4a) and a second electric motor (4b), wherein the transmission comprises an input shaft (1) to which a mechanical power source is connectable, an output shaft (6) and a gear assembly, providing at least two different gear ratios that can be selected for transmitting mechanical power from the input shaft (1) to the output shaft (6), the first electric motor (4a) being connected to the input shaft (1) such that torque and rotation can be transmitted between the first electric motor and the input shaft, and the second electric motor (4b) being connected to the input shaft (1) via a first clutch (5a) such that torque and rotation can be transmitted between the second electric motor (4b) and the input shaft (1) and to the output shaft (6) via a second clutch (5b) such that torque and rotation can be transmitted between the second electric motor (4b) and the output shaft (6), wherein the first electric motor (4a) is connected to the second electric motor (4b) via a first clutch (5 a).

Description

Powertrain system, vehicle and method for executing gear shifting in powertrain system

Technical Field

The invention relates to a hybrid powertrain and an electric powertrain for a vehicle.

Background

The present invention provides a new and improved electric or hybrid transmission/power system.

There are many types of hybrid and electric powertrain systems. Two main types of mixing systems are commonly referred to as parallel and series mixing systems.

A simple version of a parallel hybrid system is a powertrain in which an electric motor is placed on one wheel driveshaft of the vehicle and an Internal Combustion Engine (ICE) having a transmission is placed on the other wheel driveshaft of the vehicle. In another type of parallel hybrid system, the electric motor is attached to or integrated within the main gearbox.

For cars, buses and trucks, hybrid systems are typically manufactured using a transmission type that is a variation of the automatic transmission already used in pure ICE driven versions of the vehicle type.

For automobiles, there have historically been two main types of transmissions. Automatic transmissions and manual transmissions. Both types are combined with an Internal Combustion Engine (ICE), typically a gasoline engine or a diesel engine. An old technology used in automatic transmissions is a planetary gear with multiple clutches that combine planetary gear ratios to achieve a desired gear ratio. This is combined with a starting clutch as a torque converter. Typically, such transmissions are of the type known as Automatic Transmissions (ATs). Manual transmissions are so-called lay shaft (countershaft) transmissions, in which gears are placed at two parallel shafts. The starting clutch or main clutch 3 is typically a friction-type clutch, the gear ratios (i1, i2 …) are typically mechanically engaged, and only one is engaged at the same time. The torque in the gearbox will have to be zero at each shift, which also makes the shift slow. This is a significant disadvantage for comfort, performance, emissions control and fuel economy.

A block diagram of a typical powertrain featuring an ICE, a main friction clutch 3 and a common transmission 2 is shown in fig. 1.

A schematic diagram of a powertrain featuring a generic transmission 2 with a countershaft 7 typically used for heavy commercial trucks is shown in fig. 2. The powertrain features a friction clutch 3 arranged between the transmission 2 and the ICE. The illustrated transmission has two split gears (2c), three forward gears and one reverse gear in the main portion (2a) of the transmission 2 (or gearbox). Two range gears (2b) are provided at the output shaft (6). This gives a total number of forward gears of 12 (and 4 reverse gears) 2 × 3 × 2. There are many variations of this type of transmission with fewer or more gears. Furthermore, different modules may be attached at the front and rear of these types of transmissions. A typical module is an additional slow turning gear at the input side and an additional brake for long downhill braking, called retarder (Voith) brand, may be attached at the output side.

For trucks, the most common automatic transmission is a manual transmission, such as the transmission 2 in fig. 2, which is automated by operating clutches and gears using electronically controlled actuators instead of manual clutch pedals and manual shift levers. This provides a very energy efficient and cost optimal transmission. This type of transmission is commonly referred to as an Automated Manual Transmission (AMT), also in the case where the transmission has been optimized for this use and the internal components are no longer used for any manual operation. Currently, AMT is the most common transmission on the market for the largest trucks. A disadvantage of AMT is that the torque at the driving wheels will become zero at each gear shift. This is a major drawback both for comfort and acceleration performance (loss of acceleration time). Furthermore, the loss of torque is also a challenge in controlling the ICE to meet emission standards during a shift. A typical prior art AMT is disclosed for example in US 8571772B 2.

In the past 20 years, ATs (similar to manual transmissions) with two main clutches and gears on separate shafts have also gained popularity, see fig. 3. This type of AT is commonly referred to as a two-clutch transmission, a dual clutch transmission, or a Double Shift Gearbox (DSG). This transmission may alternatively shift between two parallel gear sets to transmit torque to driven wheels (illustrated as double round wheels). This gives the opportunity to have a continuous torque transfer during the gear shift. This type of transmission is very expensive and mechanically complex in order to obtain essentially two gearboxes in one unit.

A typical prior art parallel hybrid system features an electric motor E attached to the primary input shaft 1 of the transmission of any known AT, DSG or AMT system, see fig. 4. The addition of the electric motor E does not alleviate any of the drawbacks inherent in the corresponding type of transmission. In these prior art systems, the electric motor is designed to operate at a similar speed as the ICE. A prior art parallel hybrid system featuring AMT is disclosed in WO 2007/102762a 1.

In some prior art hybrid powertrain systems, referring to fig. 5, an electric motor E is attached in parallel with the transmission 2 and has a through ratio i_xThe transmission ratio is adjusted to a more cost-optimized design possibility than the solution in fig. 4. A prior art hybrid system featuring such an arrangement is disclosed in US 2002/0082134a 1. In US 2002/0082134a1, an electric motor may be operatively connected to either or both of the input and output shafts of the transmission. The hybrid system disclosed in US 2002/0082134a1 is not optimal. For example, during a shift, it may not operate as a series hybrid, and this reduces overall efficiency and increases clutch wear. Furthermore, it is not possible to actively use electric motor E to establish zero torque at the input shaft, nor can it accelerate the input shaft faster than the ICE, as required by the disengaging/engaging gears.

A prior art transmission for reducing some of the torque interruptions in an AMT transmission is described in US 2004/0138800a 1. A variant of this transmission with an electric motor for hybrid drive is described in US 2002/0082134a 1. These transmissions are known to be feasible to manufacture and control, but have challenges in that the level of torque transferred to the output shaft during a shift is too low and/or wear in one or more clutches used during the shift is high.

We now see a large trend in electrification in the automotive industry. This is driven by both fuel economy, legislation, incentives, environmental incentives, and technological breakthroughs in batteries, fuel cells, and other related technologies.

It is an object of the present invention to provide an improved power system in which at least some of the disadvantages of the prior art power systems are avoided or alleviated.

Disclosure of Invention

The invention is defined by the appended claims and by the following:

in a first aspect, the present invention provides a powertrain system comprising a transmission, a first electric motor and a second electric motor, wherein

The transmission comprises an input shaft to which a mechanical power source can be connected, an output shaft and a gear assembly providing at least two different gear ratios that can be selected for transferring mechanical power from the input shaft to the output shaft,

-the first motor is connected to the input shaft such that torque and rotation can be transmitted between the first motor and the input shaft, an

The second electric motor is connected to the input shaft via a first clutch such that torque and rotation can be transmitted between the second electric motor and the input shaft, and is connected to the output shaft via a second clutch such that torque and rotation can be transmitted between the second electric motor and the output shaft, wherein,

the first motor is connected to the second motor via a first clutch.

In other words, the first clutch is connected to the input shaft via the first electric motor.

In other words, the first motor is connected to the second motor via the first clutch so that torque and rotation can be transmitted between the first motor and the second motor via the first clutch.

In other words, the second motor is connected to the input shaft via the first clutch so that torque and rotation can be transmitted between the second motor and the input shaft via the first clutch, and is connected to the output shaft via the second clutch so that torque and rotation can be transmitted between the second motor and the output shaft via the second clutch.

In other words, the first motor, the second motor, the first clutch, and the second clutch are interconnected such that torque and rotation can be transmitted between the input shaft and the output shaft via the first motor, the second motor, the first clutch, and the second clutch.

The term "mechanical power" is intended to mean both torque and rotation.

The terms "connected to an input shaft" and "connected to an output shaft" are intended to define any direct or indirect connection that allows torque and rotation to/from the input and output shafts, respectively. In other words, these terms may also be defined as "operatively connected to the input shaft" and "operatively connected to the output shaft".

The first aspect may alternatively be defined as a powertrain system comprising a transmission, a first electric motor, and a second electric motor, wherein,

the transmission comprises a part comprising an input shaft (or input side) to which the mechanical power source can be connected, an output shaft (or output side), and at least two different gears that can be selected for transmitting mechanical power from the input shaft to the output shaft,

The second electric motor is connected to the input shaft via a first clutch such that torque and rotation can be transmitted between the second electric motor and the input shaft, and is connected to the output shaft via a second clutch such that torque and rotation can be transmitted between the second electric motor and the output shaft.

In one embodiment of the power system according to the present invention, the first motor is electrically connected to the second motor so that the first motor can generate electric power from torque at the input shaft and transmit the generated electric power to the second motor. In other words, the first motor is electrically connected to the second motor so that the torque output of the second motor can be increased by the electric power generated by the first motor. Preferably, the first motor is electrically connected to the second motor so that the electric power generated in the first motor can be directly transmitted to the second motor, i.e., the generated electric power does not pass through a battery common to the first motor and the second motor.

In other words, the first electric motor may function as a generator to generate electric power from the torque in the input shaft.

In one embodiment of the powertrain according to the invention, the first electric motor, the second electric motor, the first clutch and the second clutch form part of a torque transmission path bypassing (in other words, being parallel to) at least two different gears, the torque transmission path being arranged to transmit torque from the input shaft to the output shaft during a gear shift, i.e. during a gear shift between the at least two different gears of the transmission.

In one embodiment, the powertrain according to the invention is characterized by a torque transmission path that bypasses (or is parallel to) the at least two different gears, includes the first electric motor, the second electric motor, the first clutch and the second clutch, and can transmit torque from the input shaft to the output shaft during a gear shift (i.e., during a gear shift between the at least two different gears of the transmission).

In one embodiment of the power system according to the invention the mechanical power source is an internal combustion engine or at least one electric motor.

In one embodiment of the power system according to the invention, the at least one electric motor is preferably a first electric motor, optionally in combination with a second electric motor.

In one embodiment of the powertrain according to the invention, the first electric motor is connected to the input shaft via a third clutch.

In one embodiment of the powertrain according to the invention, the mechanical power source is an Internal Combustion Engine (ICE) connected to the transmission input via a main clutch.

In one embodiment of the power system according to the invention, the first electric motor is connected to the input shaft via a first gear, and the second electric motor is connected to the output shaft via a second gear.

In one embodiment of the powertrain according to the invention, the first clutch and the second clutch are connected to a first actuator and a second actuator, respectively, and the first actuator and the second actuator are electronically controlled. The first and second actuators are connected to an electronic control system that provides an optimal or desired level of torque to the input shaft and/or the output shaft during a gear shift. The electronic control system may also be connected to a shift actuator in the transmission.

In one embodiment of the powertrain according to the invention, any one of the first clutch, the second clutch, the third clutch and the main clutch may be operable at a torque level controllable between zero and a maximum torque level. The clutch may preferably be a friction clutch. At least one of the clutches may be of the type that is capable of increasing torque through a speed differential across the clutch.

In one embodiment, a power system according to the present invention includes a power source connected to a first motor and a second motor. The power source may be a battery, a capacitor, a fuel cell, or any combination thereof.

In one embodiment, a powertrain according to the present invention includes a drive wheel to which an output shaft is coupled.

In one embodiment of the powertrain according to the invention, the transmission is characterized by comprising at least a portion of a countershaft transmission.

In one embodiment of the power system according to the present invention, either one of the first electric motor and the second electric motor is connected to the input shaft or the output shaft via a counter shaft of a counter shaft transmission.

In one embodiment of the power system according to the present invention, either one of the first electric motor and the second electric motor is connected to the input shaft or the output shaft via a gear in the transmission.

In one embodiment of the powertrain according to the invention, the torques in the first electric motor and the first clutch and the second electric motor and the second clutch may be controlled by a central control unit.

In a second aspect, the invention provides a vehicle comprising a powertrain according to the first aspect.

In a third aspect, the invention provides a method of performing a shift from low to high in a powertrain according to the first aspect, comprising the steps of:

a. the torque in the first motor and the first clutch is controlled to be equal to the torque in the main clutch.

b. Transmitting torque to the output shaft by engaging the second clutch;

c. disengaging the low gear;

d. reducing the rotation speed of the input shaft by making the torque in the first electric motor 4a and the first clutch 5a higher than the torque in the main clutch 3; and

e. the high gear is engaged when the rotational speed of the input shaft is synchronized with the high gear and the torque in the first electric motor and the first clutch is equal to the torque in the main clutch.

In other words, step a entails controlling the resultant or combined torque provided to the input shaft by the first electric motor and the first clutch. In step a, the first clutch is at least slipping, i.e. not fully closed.

The torque in the first electric motor and the first clutch may be controlled by operating the first clutch and/or by controlling the power supplied to the first electric motor.

With regard to step d, it should be noted that the torque in the second clutch will normally be higher than the torque in the first clutch due to the torque from the second motor, and the kinetic energy in the second motor is used when reducing the rotational speed of the input shaft.

Performing a shift from low to high gear in a powertrain according to the first aspect requires shifting between at least two different gear ratios of the gear assembly.

The powertrain according to the first aspect may be defined as including a driven wheel operatively connected to the output shaft, and step b may be defined as transmitting torque to the driven wheel by engaging the second clutch.

In one embodiment, the method according to the third aspect comprises the step of establishing a required torque in the input shaft by any combination of the first electric motor, the second electric motor and the ICE after engagement of the high gear. In other words, after engaging high gear, a desired torque is established in the input shaft by providing torque to the input shaft from any combination of the first electric motor, the second electric motor, and the ICE.

In one embodiment of the method according to the third aspect, the required torque is obtained by establishing the total torque from the ICE in the main clutch 3.

In one embodiment of the method according to the third aspect, step a is preceded by the step of driving the input shaft by any one of the first electric motor, the second electric motor and the ICE, wherein any one of the first clutch and the second clutch is open or closed.

In one embodiment of the method according to the third aspect, step a is preceded by the step of driving the output shaft by the first electric motor and/or the second electric motor, wherein the first clutch is opened or closed and the second clutch is closed.

In one embodiment of the method according to the third aspect, step a is preceded by the step of operating a first electric motor and a second electric motor in rotational engagement with the input shaft of the transmission, wherein the first clutch is closed and the second clutch is open.

In one embodiment of the method according to the third aspect, step a is preceded by the step of operating the ICE in rotational engagement with the input shaft of the transmission via the master clutch.

The terms "closed" and "open" may optionally be replaced by the terms "disengaged" and "engaged", respectively. When engaged, the first clutch and the second clutch transmit torque up to a torque capacity.

In a fourth aspect, the present invention provides a method of performing a shift from low to high in a powertrain according to the first aspect, comprising the steps of:

a. controlling the torque in the first motor and the first clutch to be equal to the torque in the input shaft;

b. transmitting torque to the output shaft by engaging the second clutch;

c. disengaging the low gear;

d. reducing the rotation speed of the input shaft by making the torque in the first motor 4a and the first clutch higher than the torque in the input shaft; and

e. the high gear is engaged when the rotational speed of the input shaft is synchronized with the high gear and the torque in the first electric motor and the first clutch is equal to the torque in the input shaft.

In one embodiment, the method according to the fourth aspect comprises the step of disengaging the second clutch and transferring torque from the second electric motor to the input shaft after the step of engaging the high gear. In other words, after the step of engaging the high gear, the first electric motor, the second electric motor, the first clutch and the second clutch are controlled, for example by a central control unit, to obtain the required torque in the input shaft.

In one embodiment of the method according to the fourth aspect, step a is preceded by the step of driving the input shaft by either one of a first motor and a second motor, wherein either one of the first clutch and the second clutch is open or closed.

In one embodiment of the method according to the fourth aspect, step a is preceded by the step of operating a first electric motor and a second electric motor in rotational engagement with the input shaft of the transmission, wherein the first clutch is closed and the second clutch is open.

In a fifth aspect, the present invention provides a method of performing a shift from high to low in a powertrain according to the first aspect, comprising the steps of:

a. controlling the torque in the first electric motor (4a) and the first clutch (5a) to be equal to the torque in the main clutch (3);

b. transmitting torque to the output shaft (6) by engaging the second clutch 5 b;

c. disengaging the high gear;

d. increasing the rotational speed of the input shaft (1) by making the torque in the first electric motor (4a) and the first clutch (5a) higher than the torque in the main clutch (3); and

e. the low gear is engaged when the speed of the input shaft (1) is synchronized with the low gear and the torque in the first electric motor (4a) and the first clutch (5a) is controlled to be equal to the torque in the main clutch (3).

The powertrain according to the first aspect may be defined as including a driven wheel operatively connected to the output shaft, and step b may be defined as transmitting torque to the driven wheel by engaging the second clutch. In one embodiment, the engaged second clutch is slipping. A slipping, engaged clutch may transmit a maximum torque or less, but not a maximum rotational speed (rotational speed).

In step d of the method according to the fifth aspect, the main clutch is slipping. It should be noted that the powertrain of the present invention has significant advantageous effects in that the second electric motor can provide negative torque at the output shaft, while the first electric motor can quickly accelerate the input shaft to a desired speed and in this way shift gears as quickly as possible.

In one embodiment, the method according to the fifth aspect comprises the step of establishing a required torque in the input shaft by any combination of the first electric motor, the second electric motor and the ICE after low gear engagement. In other words, after low gear engagement, a desired torque is established in the input shaft by providing torque to the input shaft from any combination of the first electric motor, the second electric motor, and the ICE.

In one embodiment of the method according to the fifth aspect, the required torque is obtained by establishing the total torque from the ICE in the main clutch.

In one embodiment of the method according to the fifth aspect, step a is preceded by the step of driving the input shaft by any one of the first electric motor, the second electric motor and the ICE, wherein any one of the first clutch and the second clutch is open or closed.

In one embodiment of the method according to the fifth aspect, step a is preceded by the step of operating a first electric motor and a second electric motor in rotational engagement with the input shaft of the transmission, wherein the first clutch is closed and the second clutch is open.

In one embodiment of the method according to the fifth aspect, step a is preceded by the step of operating the ICE in rotational engagement with the input shaft of the transmission via the main clutch.

In a sixth aspect, the present invention provides a method of performing a shift from high to low in a powertrain according to the first aspect, comprising the steps of:

b. transmitting torque to the output shaft by engaging the second clutch;

c. disengaging the high gear;

d. increasing the input shaft speed (i.e., rotational speed, revolutions per minute) by making the torque in the first motor and the first clutch higher than the torque in the input shaft; and

e. the low gear is engaged when the input shaft speed is synchronized with the low gear and the torque in the first electric motor and the first clutch is controlled to be equal to the torque in the input shaft.

In other words, step a entails controlling the resultant or combined torque provided to the input shaft by the first electric motor and the first clutch. In step a, the first clutch is at least slipping.

The powertrain according to the first aspect may be defined as including a driven wheel operatively connected to the output shaft, and step b may be defined as transmitting torque to the driven wheel by engaging the second clutch. In one embodiment, the engaged second clutch is slipping, i.e. not transmitting the maximum possible torque.

It should be noted that the powertrain of the present invention has significant advantageous effects in that the second electric motor can provide negative torque at the output shaft, while the first electric motor can quickly accelerate the input shaft to a desired speed and in this way shift gears as quickly as possible.

In one embodiment, the method according to the sixth aspect comprises the step of establishing a desired torque in the input shaft by any combination of the first and second electric motors after the low gear engagement. In other words, after low gear engagement, a desired torque is established in the input shaft by providing torque to the input shaft from any combination of the first and second electric motors.

In one embodiment of the method according to the sixth aspect, step a is preceded by the step of driving the input shaft by either one of a first motor and a second motor, wherein either one of the first clutch and the second clutch is opened or closed.

In one embodiment of the method according to the sixth aspect, step a is preceded by the step of operating a first electric motor and a second electric motor in rotational engagement with the input shaft of the transmission, wherein the first clutch is closed and the second clutch is open.

In one embodiment, the method according to the sixth aspect comprises the step of disengaging the second clutch and transmitting torque from the second electric motor to the input shaft after the step of engaging the low gear.

In a seventh aspect, the present invention provides a method of transmitting torque in the powertrain system according to the first aspect, comprising the steps of:

-disengaging the first clutch and engaging the second clutch;

-transferring torque from the input shaft to the first electric motor and operating the first electric motor as a generator;

-transferring the electric power generated by the first electric motor to the second electric motor;

-generating a torque in the second electric motor by using the electric power transmitted from the first electric motor; and

-transmitting the torque generated in the second electric motor to the output shaft.

In some embodiments of the method according to the seventh aspect, the step of generating torque in the second electric motor by using the electric power transmitted from the first electric motor may be defined as increasing torque in the second electric motor by using the electric power transmitted from the first electric motor.

By transferring the electric power generated in the first electric motor to the second electric motor, the torque from the second electric motor can be increased in a short time, advantageously in a highly energy-efficient manner.

In an eighth aspect, the present invention provides a method of obtaining maximum torque at an output shaft of a powertrain according to the first aspect, comprising the steps of:

operating the first electric motor 4a and the second electric motor 4b with maximum torque in the same direction of rotation, while engaging both the first clutch 5a and the second clutch 5 b. The first and second clutches transmit maximum torque, but may have controlled slip.

In one embodiment of the eighth aspect, the powertrain is characterized by an ICE connected to the input shaft via a main clutch, and the method comprises the steps of:

-operating the ICE to provide torque in the same rotational direction as torque from the first and second electric motors while engaging the main clutch. The main clutch preferably transmits maximum torque, but may have controlled slip.

In one embodiment of the eighth aspect, the ICE provides its maximum torque.

In one embodiment of the eighth aspect, the method is performed during a gear shift, preferably during and/or after the step of disengaging a high or low gear in the transmission, i.e. during a gear ratio shift.

The method according to the third to sixth aspects may comprise the steps as defined above, wherein a desired torque is established in the input shaft. The required torque will typically be calculated as a result of a high level of torque input to a transmission controller or central control unit (e.g., driver via pedal, cruise control, traction control, or other high level control). From the transmission controller, the electric motors in the powertrain can be controlled to impart a desired torque to the input shaft, i.e., the desired torque is calculated by the transmission controller based on the desired torque or rotational speed in the output shaft.

Drawings

Embodiments of the present invention are described in detail with reference to the following drawings:

FIG. 1 is a block diagram of a prior art powertrain featuring a transmission.

FIG. 2 is a detailed schematic diagram of a prior art powertrain for a heavy commercial truck.

FIG. 3 is a block diagram of a powertrain featuring a prior art transmission system, commonly referred to as a dual clutch transmission, or Dual Shift Gearbox (DSG).

Fig. 4 is a prior art powertrain of a hybrid system for heavy trucks and buses, wherein an electric motor E is attached to an input shaft 1 of an Automated Manual Transmission (AMT).

FIG. 5 is a prior art power system having substantially the same functionality as the power system shown in FIG. 4.

FIG. 6 is a block diagram of an exemplary powertrain system according to the present invention.

FIG. 7 is a block diagram of an exemplary powertrain of the present invention wherein the powertrain is fully driven by an electric motor, i.e., no ICE is connected to the powertrain.

FIG. 8 is a detailed schematic diagram illustrating an exemplary powertrain system according to the present disclosure. The schematic diagram is based on the prior art power system in fig. 2.

FIG. 9 is a detailed schematic illustrating an exemplary powertrain system according to the present disclosure. The schematic diagram is based on the prior art transmission of fig. 2.

FIG. 10 is a detailed schematic illustrating an exemplary powertrain system according to the present disclosure.

FIG. 11 is a detailed schematic illustrating an exemplary powertrain system according to the present disclosure.

FIG. 12 is a detailed schematic diagram of the powertrain of FIG. 11 featuring an electronically controlled actuator.

FIG. 13 is a detailed schematic diagram illustrating an exemplary powertrain system according to the present disclosure.

FIG. 14 is a block diagram of an exemplary powertrain system according to the present invention.

FIG. 15 is a block diagram of an exemplary powertrain system according to the present invention.

FIG. 16 is a block diagram of an exemplary powertrain system according to the present invention.

FIG. 17 is a detailed schematic illustrating an exemplary powertrain system according to the present disclosure. The powertrain is similar to that of fig. 8 without the ICE.

FIG. 18 is a perspective view of an exemplary power system according to the schematic diagrams in FIGS. 8 and 17.

FIG. 19 is a detailed schematic illustrating an exemplary powertrain system according to the present disclosure.

FIG. 20 is a graph illustrating calculated torque levels for an exemplary shift process using the powertrain system according to the present disclosure.

FIG. 21 is a graph illustrating calculated torque levels for an exemplary shift process using the powertrain system according to the present disclosure.

Detailed Description

Based on the prior art described in the background section and illustrated in fig. 1 to 5, the applicant has developed a very advantageous power system, which will be described in more detail with reference to fig. 6 to 21. The same reference numerals have been provided throughout the application for the same or similar features.

An embodiment of a hybrid system according to the present invention is illustrated by using the block diagram in fig. 6. The powertrain includes an ICE connected to an input shaft 1 (or input side) of a transmission 2 (or gearbox) via a main clutch 3, a first electric motor 4a, a second electric motor 4b, a first clutch 5a and a second clutch 5 b. The first motor 4a is preferably via at least one gear i_xThe (first gear) is operatively connected to the input shaft 1 and to the second electric motor 4b via the first clutch 5 a. The second electric motor 4b is connected via a second clutch 5b and at least one gear i_y(or second gear) is operatively connected to an output shaft 6 (or output side) of the transmission 2, and is connected to the input shaft 1 via a first clutch 5 a. The arrangement of the

electric motors

4a, 4b and the first and

second clutches

5a, 5b ensures that torque can be transmitted between the input and output shafts in a flexible and controllable manner. In other words, the

electric motors

4a, 4b and the first and

second clutches

5a, 5b form part of a torque transmission path capable of transmitting torque and rotation between the input shaft 1 and the output shaft 6 of the transmission. The detailed configuration of the torque transfer paths may vary depending on the type of transmission and space requirements. Except thatIn addition to having at least two gears in the transmission 2 (i.e., a gear assembly providing at least two gears), the powertrain of the present invention may also include any suitable additional gears, such as a slow gear (cruise gear) and a split gear (split gear). Additional gears may be included in the transmission 2 or connected to an input or output shaft of the transmission 2. See for example the embodiment of fig. 8, in which the transmission 2 is composed of a main part 2a, a slow turning gear 2b and a split gear 2 c.

As shown in fig. 6, the combination of having two

electric motors

4a, 4b interconnected via

clutches

5a, 5b provides several advantageous effects. The main advantage is the possibility to transfer torque during a gear shift. Further, the disclosed combination of two clutches and two electric motors provides significantly increased torque transfer performance by using rotational kinetic energy in the system during gear shifts. Although not shown in fig. 6, the power system of the invention includes a power source, such as a battery, arranged to provide electrical power to either of the two

electric motors

4a, 4b when required, and to store electrical power received from either of the two electric motors when acting as a generator. In addition, the first electric motor 4a may be electrically connected to the second electric motor 4b, so that electric power generated in the first electric motor 4a may be transmitted to the second electric motor 4b when the first electric motor 4a functions as a generator. In a preferred embodiment, the first motor 4a is electrically connected to the second motor 4b, so that the electric power generated in the first motor 4a can be directly transferred to the second motor 4b, i.e. without passing through a common power supply (not shown). The latter feature is very advantageous because it is highly energy efficient.

Another advantage of the powertrain of the present invention is that no expensive brakes and/or components are required for synchronizing the input shaft speed during gear shifting, as synchronization can be handled by at least the first electric motor 4a, optionally in combination with the first clutch 5 a.

During a gear ratio upshift, the two

electric motors

4a, 4b will compensate for the torque loss at the output shaft 6 using their peak power performance available only for a short period of time, the torque transmission path extending between the input shaft 1 and the output shaft 6 and being able to transmit torque over the two

clutches

5a, 5 b. In addition to or instead of transmitting torque/mechanical power from the input shaft 1 over the first clutch 5a, the first electric motor 4a may receive torque/mechanical power from the input shaft 1 and supply electric power to the second electric motor 4b, which in turn will supply torque/mechanical power to the output shaft 6 (and thus to the driven wheels 8) via the second clutch 5b during a gear shift. In addition to or instead of the power generated by the first motor 4a, the torque from the second motor 4b to the driven wheels 8 may be increased by power from a battery or other power source.

In an electric drive situation, i.e. where only the electric motor is used to drive the vehicle, the most common situation will be when the first clutch 5a is fully engaged to transmit torque, while the second clutch 5b is fully open, i.e. not transmitting any torque.

The present invention requires the use of two separate motors, a first motor 4a and a second motor 4b, which in combination provide the required torque/mechanical power. The use of two motors, as opposed to a single motor, can be cost effective, which may seem counterintuitive, but the cost of a motor having a size suitable for electric drive is substantially proportional to the torque and mechanical power of the motor. Thus, the cost difference of electrically generated torque/mechanical power obtained by using a single large motor or a combination of two small motors is small.

Although the cost difference between using a single large motor and two smaller motors is small, there is a large difference in function. The combination of two motors of the present invention can be used to a large extent as a mechanical gearbox by converting a lower torque at high rpm to a higher torque at a lower speed. Since the motor can be executed in a short time with a much higher mechanical power output, this performance is very consistent with the need during gear shifts that occur in a relatively short time (typically less than 2-3 seconds).

Thus, when used as a hybrid powertrain, the powertrain of the present invention will improve the performance of the transmission system because it makes it possible for a transmission (e.g., an AMT transmission) to transmit torque (between the input shaft/input side to the output shaft/output side) during a gear shift. This is a very advantageous feature as it allows the best possible acceleration, maintains speed during uphill driving, improves comfort, minimizes emissions during gear shifts and provides overall improved efficiency. By using a combination of two electric motors in a hybrid powertrain, the behavior of the powertrain will be similar to that obtainable only by a powertrain featuring a more complex and expensive transmission system, such as AT or DSG. For trucks this means a significant increase in customer value. Furthermore, the powertrain of the present invention can be constructed from a standard AMT transmission by adding the required electric motor and clutch as modules. The latter option may be a particularly attractive solution for truck manufacturers. When used in a passenger car, the powertrain of the present invention provides a significant reduction in component costs by eliminating the need for an expensive transmission with torque transfer during gear ratio shifts.

The powertrain of the present invention may be configured as a powertrain that operates primarily in an ICE-driven mode to a system that may operate primarily or exclusively in an electric-only mode, depending on customer requirements for functionality and economy. In other words, the power system of the present invention may be configured as a hybrid system featuring an ICE and an electric motor for providing power, and a purely electric system, wherein all power is provided by the electric motor.

There are many different technologies for electric motors used for propulsion of electric vehicles. The powertrain of the present invention may use any of these known motor technologies, i.e., any of DC series motors, brushless DC motors, Permanent Magnet Synchronous Motors (PMSM), three-phase alternating current induction motors, and Switched Reluctance Motors (SRM). Each type of motor may have different performance characteristics. By using the power system of the invention, an optimal combination of motors can be applied. For example, some motor principles are known to have very low torque at zero speed, but other advantageous characteristics, such as high efficiency during operation. By using the powertrain of the present invention, the type of electric motor can be optimized, for example, because the second electric motor 4b has a very low torque at zero speed, but has a high efficiency during operation (i.e., in a defined speed range above zero), while the first electric motor 4a can provide a high torque at zero speed, but is somewhat less efficient during operation. Using the latter combination of motors, a vehicle starting at zero speed in an electric-only drive mode with a low gear engaged in the transmission 2 will be able to operate the clutch 5a at a slipping speed, so both the first and second

electric motors

4a, 4b can execute at their maximum torque to roll the vehicle.

The

clutch

3, 5a, 5b used in the inventive power system may in many cases be any suitable type of friction clutch, wherein the transmission of torque is accomplished by pushing at least two friction surfaces against each other. However, the inventive power system may also comprise clutches according to other known clutch principles, such as:

a friction clutch combined with centrifugal operation;

clutches based on the hydraulic principle (i.e., known as torque converters) in which one rotating member rotates the other via a fluid (transmission oil);

clutches with mechanical connections for transmitting rotation, for example dog clutches;

clutches in which the viscosity of the fluid in the clutch is changed by thermal or magnetic properties to transmit torque; and

any combination of the above principles.

In order to obtain a compact design of the power system, it may be advantageous to use a friction clutch with a plurality of clutch discs.

To control torque in the powertrain of the present invention during a gear shift, the first electric motor 4a, the second electric motor 4b, the first clutch 5a, the second clutch 5b, and the optional main clutch 3 (depending on whether the powertrain features an ICE) are the components that are the primary focus of the control software and strategy. Although the

electric motors

4a, 4b can surprisingly change torque quickly in as little as 20-30ms, the

clutches

5a, 5b are typically relatively slow because of the time required for the clutch plates to move and build up pressure on the clutch plates. The corresponding time for a significant change in torque through the friction clutch may be about 100 and 200 ms. The rapid torque change of the electric motor can be used in many gear shifting processes/methods as disclosed below. The fast torque change is particularly useful in higher positive torque upshifts after disengagement of the low gear, as described below in method I. This is an operation where the input shaft speed is reduced and synchronized to a new higher gear. The method can be briefly described as first operating the first electric motor 4a with a high positive torque output and causing the first clutch 5a to transfer torque from both the main clutch 3 and the first electric motor 4 a. In order to apply torque quickly to reduce the input shaft rotational speed (rotational speed), the first electric motor 4a is reduced as quickly as possible and may become negative torque to decelerate the input shaft 1. The first clutch 5a will increase the torque as quickly as possible, but the torque is applied significantly slower than the first electric motor 4 a.

The purely electric drive power system according to the invention is shown in a block diagram in fig. 7. In contrast to the hybrid powertrain in fig. 6, the powertrain is completely driven by the

electric motors

4a, 4b, i.e. no internal combustion engine is connected to the powertrain. For all-electric vehicles that will need to operate at high speeds for longer periods of time and at very low speeds for longer periods of time, there are many situations where a transmission featuring at least two gears would be advantageous. Similar to the embodiment of fig. 6, the embodiment of fig. 7 may be shifted without torque interruption. In an electric-only drive powertrain, the at least two gears will allow for optimization of the electric motor in terms of efficiency.

For simplicity, the present invention is described below with reference to a powertrain system featuring an ICE, i.e., a hybrid powertrain system. However, the features described in connection with the hybrid powertrain shown in fig. 8-16 may also be used with a corresponding powertrain that does not have an ICE and is driven solely by an electric motor. Two exemplary powertrain systems for electric drive only are shown in fig. 17 and 19.

FIG. 8 illustrates an exemplary hybrid powertrain system according to the present invention featuring a conventional countershaft transmission as shown in FIG. 2. Most common transmissions have a modular design, wherein modules featuring e.g. additional slow turning gears may be attached at the input side of the transmission 2 featuring a main gear 2a (or main part of the transmission), a split gear 2c and a range gear 2b (the transmission may be referred to as a gearbox). In FIG. 8, the powertrain of the present invention is based on a standard heavy truck transmission, wherein the standard components of the transmission are unchanged. The first electric motor 4a is connected to the input shaft 1 (or input side) of the transmission in the same way and position as the modules comprising additional slow turning gears are normally connected. The second electric motor 4b is connected to the output shaft 6 (or output side) in the same manner and position as the reducer module is normally connected. In the embodiment of fig. 8, the first and second motors provide the same functionality as is typically provided by a slow turning gear and reducer system. Alternatively, the powertrain of the present invention may include any additional slow turning gear and reducer modules, if desired. In this description, the specific features described by the term "layshaft" are intended to mean a shaft comprising a gear and running parallel to the input shaft of the transmission (i.e. the layshaft 7 as shown in fig. 8).

Fig. 9 shows an exemplary hybrid system according to the invention featuring a transmission similar to the transmission shown in fig. 2, wherein the transmission 2 is slightly optimized for the hybrid system. In fig. 9, the internal gear is redesigned, but the range gear is essentially unchanged and the reverse gear is replaced by the forward gear. Reverse drive can be obtained only by rotating at least the first electric motor 4a in the opposite direction. A further simplification of the transmission in fig. 2 is achieved by removing the split gear arrangement and by connecting the first electric motor to the input shaft 1 via gear 9 on the countershaft 7 of the transmission. The transmission/gearbox of fig. 9 has 5 main gears by 2 range gears (10 gears total). Additionally, when both

clutches

5a, 5b of the powertrain of the present invention are in a fully engaged state (i.e., transmitting full torque), they will operate as additional gears. The redesign of the internal gears is expected to provide a cost reduction compared to the conventional transmission of fig. 2. For many current transmissions, such changes in internal components would require no, or very little, changes to the standard gearbox housing of the actuator design and the master starting clutch 3 for shifting.

FIG. 10 illustrates a detailed schematic diagram of another exemplary embodiment of a power system according to the present disclosure. The transmission 2 is a countershaft gearbox with 5 forward gears and 1 reverse gear. In this case, the countershaft gearbox can be made without synchronizers, which further reduces the cost of the gearbox and increases robustness. It is typical for countershaft gearboxes to use two parallel shafts and to use a splined sleeve that connects selected gears to the shafts so that torque can be transferred. The shaft running parallel to the input shaft of the transmission 2 is usually referred to as countershaft 7. When multiple gear ratios are required, these gearboxes are referred to as transmissions with the highest efficiency and lowest cost. In this embodiment, the first electric motor 4a and the second electric motor 4b are connected to the output shaft 6 via a gear 10 on the counter shaft 7.

Fig. 11 shows a detailed schematic of a mechanical layout with the same functionality as the powertrain in fig. 10, but with minor changes so that the two

clutches

5a, 5b are placed in the same area and provide better integration of the clutches and clutch actuators (see fig. 12). In addition, this layout also provides more space for the motor and clutch in the longitudinal direction of the powertrain.

Fig. 12 shows the powertrain of fig. 11 and shows how the powertrain of the present invention requires electronically controlled actuation and shifting of all

clutches

3, 5a and 5 b. The actuation may be performed by any suitable electronically controllable actuator 8a-8f, including an electric motor, an electromagnetic solenoid, an electro-hydraulic or pneumatic actuator. The various actuators 8a-8f may be controlled by a central control unit (not shown) based on input from the driver (e.g., via drive and brake pedals) and optionally via data provided from a navigation system. Similar control systems are well known in the art and are described in, for example, US 2002/0082134a1 and WO 2007/102762a 1.

Fig. 13 shows a variant of the invention, in which a typical configuration is characterized by the mechanical output power of the ICE being relatively smaller than the combined mechanical output power of the first electric motor 4a and the second electric motor 4 b. The combined torque and power output of the three power sources ICE, 4a, 4b is required by the vehicle. In this configuration, the ICE will typically operate in a higher speed range and have a lower torque output. This makes it possible to let the typical main component 2a of the transmission 2 (the component of the transmission featuring the countershaft 7) run at a higher rotational speed and lower torque, resulting in a more compact transmission. This improvement is made possible by having the ratio before the final variable ratio, commonly referred to as range gear 2 b. In the present embodiment, a planetary range gear 2b is used, however, any other suitable type of range gear, such as a countershaft range gear, may alternatively be used. The first electric motor 4a is connected to the input shaft 1 of the transmission 2 via a gear 11 in the main part 2a of the transmission and the countershaft 7.

FIG. 14 illustrates a block diagram of an exemplary power system according to the present disclosure. The powertrain is an ICE-driven hybrid powertrain in which the electric motor 4a is placed concentrically with and fixed to the input shaft of the transmission 2. The second motor 4b is arranged as shown in fig. 6.

FIG. 15 illustrates a block diagram of an exemplary powertrain system according to the present invention. In this embodiment, the first electric motor 4a is connected to the main component 2a of the transmission 2 (i.e., includes the main gear i)₁、i₂、i₃...i_nAnd the second electric motor 4b is connected to the output shaft 6 of the main part 2a) of the transmission. In addition to the main part 2a, the transmission 2 features a range gear 2b and a split gear 2 c.

Fig. 16 shows an exemplary drive train according to the invention, which is characterized by an additional clutch, i.e. a third clutch 5c, arranged between the first electric motor 4a and the input shaft 1. The third clutch 5c provides additional flexibility and further improved function and efficiency in for example the following situations:

a. in driving situations where it is advantageous to connect the first electric motor 4a directly to the output shaft. Especially above i_y/i_xThis would be the case for a gear ratio shift.

b. In the case of driving in which the first electric motor 4a has performed an action of disengaging/engaging and/or synchronizing the rotational speed of the input shaft 1, it will be possible to open the third clutch 5c and close the first clutch 5a, and to supply torque from the first electric motor 4a to the output shaft 1 without any slip/loss in the first clutch 5 a.

In fig. 18, which shows a perspective view of an exemplary powertrain according to the schematic of fig. 17, the powertrain in fig. 18 will correspond to the schematic in fig. 8 by connecting the powertrain to the ICE via the main clutch.

FIG. 19 shows a power system specifically designed for use with only an electric motor. This powertrain is designed such that when the first clutch 5a and the second clutch 5b are fully engaged, there will be 4 gears and additional gears available in the transmission 2. This powertrain configuration offers the possibility of having a wide range of transmission ratios, which is necessary to obtain an optimized system for heavy vehicles and/or for vehicles using a maximum of continuous power from the electric motor for a longer period of time.

The exemplary embodiments disclosed above illustrate various technical solutions for obtaining a power system according to the invention. It should be noted, however, that this is not an exhaustive disclosure of all embodiments of the invention. Based on this disclosure, the skilled person will be able to construct alternative power systems, which however will fall within the scope of the invention as defined by the appended claims.

The exemplary powertrain system disclosed above provides increased torque control during a shift. The graphs in fig. 20 and 21 show how the torque is controlled during the different gear shifts. The graph shows how torque can be transmitted from the ICE (T _ ICE), the first electric motor 4a (T _ E1), and the second electric motor 4b (T _ E2) without using further improved torque levels that can be achieved by the rotational kinetic energy connected to the ICE and the first and second

electric motors

4a and 4 b. The graph is calculated assuming that the ICE is relatively large, i.e., of similar size to an ICE in a heavy commercial truck, is connected to a typical 12-speed AMT transmission, and the first and second

electric motors

4a and 4b are relatively small in size (torque) compared to the ICE. Shifts are made at full torque at the ICE. Many shifts are accomplished at torque levels lower than the full ICE torque level, and in these cases the transfer of electric power by the first and second

electric motors

4a, 4b will be a greater portion of the torque at the output shaft.

Fig. 20 shows a shift from 5 th to 6 th gear. In these graphs we set the torque from the ICE to 1 and for typical gear ratios of a 12-speed AMT transmission, for 5 th gears close to 4, 5 and 6 th gears close to 3, 5. Thus, the output shaft torque will be the same as the gear ratio in the relative torque. In this shift, the powertrain according to the present invention may be used to establish the highest possible torque fill. This means that the ICE and the first and second

electric motors

4a, 4b will operate as electric motors and provide mechanical power into the system. Thus, the torque available at the output shaft by using the powertrain of the present invention will be:

T_sum＝(T_E₁×i_y)+(T_E₂×i_y)+(T_ICE×(i_y/i_x))

when the gears are disengaged, the only torque at the output shaft will be provided by the combined torque output of the first and second

electric motors

4a, 4b and the ICE via the first and

second clutches

5a, 5 b. This shift follows the description of the positive torque upshift control strategy disclosed below.

Fig. 21 shows a shift from 9 th to 10 th gear and then from 10 th to 11 th gear. Since the shift is in a higher gear than the shift shown in fig. 20, the torque on the output shaft is significantly lower than the torque shown in fig. 20. Therefore, the torque from the second electric motor 4b (T _ E2) will be the largest portion of the torque transmitted to the output shaft during the gear shift. It is also important to note that this shifting is operated with the first electric motor 4a operating as a generator, thus reducing torque in the first clutch 5a, thereby improving overall efficiency and reducing wear in the first clutch 5 a.In this example, i_y/i_xThe gear ratio is determined to be the same as that of the 10 th gear. This results in a significant difference between the two shifts. For gears 9 to 10, the ICE will be able to add additional torque to the output shaft. For a shift from 10 th to 11 th gear, the difference in rotational speed makes it impossible to increase the torque at the output shaft, but the shift will be made with the first clutch 5a open and the second clutch 5b closed, and all power from the input shaft 1 is electrically transmitted to the output shaft via the first electric motor 4a and the second electric motor 4 b.

In many cases, powertrain solutions with output power and torque of the ICE less than or similar to the first and second

electric motors

4a and 4b may be optimal solutions in terms of fuel economy. This will also provide a powertrain solution where the torque fill will be significantly higher, especially in the lower speed gears.

The power system of the invention as described above has several advantageous functional features in common, and the technical basis of these features is explained below:

the electric motor can be designed to have a much better relationship between torque and moment of inertia for rotational acceleration than a typical ICE. A high rotational acceleration is very useful for the first electric motor 4a, since it provides great advantages in controlling the input shaft to obtain the correct rotational speed (rotational speed) as fast as possible. Another advantage of the motor is the possibility of very fast variations in the torque from the motor. These two characteristics of the motor are used in the power system of the present invention in a non-obvious manner.

When the rotation speed of the input shaft 1 is controlled by the above characteristics together with the first electric motor 4a, the second electric motor 4b has a large effect on supplying the torque to the output shaft 6. The torque is mainly generated by electric power in the second electric motor 4 b. Thus, in many embodiments of the powertrain of the present invention, the second electric motor may be larger than the first electric motor. The second electric motor 4b may additionally be supercharged using the inertia in the second electric motor 4b and partly in the first clutch 5a and the second clutch 5b and the connecting gear 2 between them, to improve the torque to the output shaft 6, in particular during short periods of gear disengagement and engagement. At this time, the rotation speed at the input shaft 1 must be kept stable, and it will be impossible to increase the torque at the output shaft 6 using the inertia of the ICE and the first electric motor 4 a.

Since the control of the rotational speed of the input shaft 1 and the supply of torque to the output shaft 6 should be performed simultaneously, the advantage of having a powertrain comprising two electric motors and two clutches is greater as in the exemplary embodiment. Advantageous effects are disclosed in more detail by the methods/processes described below.

It should be noted that while the ability to transfer torque during a shift (also referred to as torque filling, see fig. 20 and 21 and the description thereof) is a very advantageous effect of the present invention, it is also important that the powertrain of the present invention provide a significant reduction in shift time (i.e., increased shift speed).

Although many shifting processes/methods have maximum fuel efficiency as the primary focus, the primary additional advantages of the powertrain of the present invention are increased acceleration and comfort.

All of the above described embodiments of the powertrain of the present invention provide several advantages associated with an improved and efficient shifting process/method. Next, the most important shift process/method is described with reference to the block diagram in fig. 6.

I. Positive torque upshift

The positive torque upshift control strategy as shown in fig. 20 may be executed by referring to the block diagram in fig. 6 by:

1. the first motor 4a and the second motor 4b operate in rotational engagement with the input shaft 1 of the gearbox. The first clutch 5a is closed and the second clutch 5b is open.

2. The torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3. (at least the first clutch 5a is slipping). By engaging the slipping second clutch 5b, torque is transmitted to the driven wheels 8 (via the output shaft/side 6). It should be noted that the torque in the second clutch 5b will generally be higher than the torque in the first clutch 5a due to the torque from the second electric motor 4 b. When the second motor 4b is brake-decelerated, the kinetic energy in the second motor 4b is used.

3. Disengaging the low gear.

4. Since the torque in the first electric motor 4a and the first clutch 5a is higher than the torque in the main clutch 3, the rotation speed of the input shaft 1 is reduced.

5. Step 6 may be performed when the rotational speed of the input shaft 1 is synchronized with the new higher gear and the torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3.

6. The new higher gear is engaged. It is to be noted that the torque in the second clutch 5b is generally higher than the torque in the first clutch 5a due to the torque from the second electric motor 4 b. When the second motor 4b is brake-decelerated, the kinetic energy in the second motor 4b is used.

7. The full torque from the ICE is established in the main clutch 3.

Additionally, it is also possible to use kinetic energy from the ICE during steps 2-6 to further increase the torque transferred during the shift. But this would require more detailed control of the main clutch 3 and the ICE. However, this is a very likely control strategy to be added to the basic control strategy described above.

The control strategy will also vary depending on the percentage of torque requested from the driver/cruise control or other input. Typically, if the first and second electric motors can keep up with the torque demand from the system, most of the torque during the shift will be transferred across the first and second electric motors. This will reduce heat and wear in the clutches in the system.

For the above i_y/i_xPositive torque upshift of transmission ratio

In most embodiments of the power system, the first electric motor 4a is via a first gear i_xIs connected to the input shaft 1, and the second motor 4B is via a second gear i_yIs connected to the output shaft 6. To transmission ratio i_y/i_xThe torque transmission capacity of the combined first clutch 5a and second clutch 5b is limited because of the gear ratio of the higher gear to be shifted in the transmission 2Higher than i_y/i_xIn a defined gear ratio, torque may not be transmitted from the input shaft 1 to the output shaft 6 via the clutch. An upshift with positive torque in a higher gear at the output shaft 6 will typically occur at the end of acceleration, and the purpose of the shift is to find the most economical gear for the driving situation (e.g. stable cruise speed). Thus, the demand for torque filling in the higher gears is somewhat lower than the demand for torque filling in the lower and intermediate ratio gears.

To above i_y/i_xA positive torque upshift of the gear ratio of (1) may be performed by:

1. the first electric motor 4a and the second electric motor 4b operate in rotational engagement with the input shaft 1 of the transmission 2. The first clutch 5a is closed and the second clutch 5b is open.

2. The first clutch 5a will start to disengage/slip (i.e. start to disengage partially) while the second electric motor 4b will accelerate to obtain a rotational speed equal to or higher than the corresponding rotational speed of the output shaft 6 on the second clutch 5 b.

3. This step may be started in parallel with the second step. The torque in the ICE will start to decrease and the main clutch 3 will start to slip (i.e. start to disengage partially) while the first electric motor 4a will start to brake the input shaft 1.

4. Once step 2 is reached, the second clutch 5b will engage the output shaft 6 and begin to accumulate torque at the output shaft 6 to compensate for the torque reduction from the action in step 3. Step 3 and step 4 will occur simultaneously.

5. The torque in the first electric motor 4a is controlled to be equal to the torque in the main clutch 3 (preferably, the first clutch 5a has zero torque — completely disengaged).

6. Disengaging the low gear while transmitting torque to the driven wheels 8. Torque to the driven wheels 8 is obtained from the second motor 4b, which is operated by electric power generated in the first motor 4a, which is obtained from a battery, or from a combination thereof, and the second motor 4b applies torque to the output shaft 6 via the second clutch 5 b.

7. The speed of the input shaft 1 is reduced by the torque in the first electric motor 4a being higher than the torque in the main clutch 3. The first clutch 5a is preferably fully disengaged and the main clutch 3 is slipping or fully disengaged.

8. When the speed of the input shaft 1 is synchronized with the new higher gear and the torque in the first electric motor 4a is controlled to be equal to the torque in the main clutch 3, the new higher gear is engaged.

9. The full torque from the ICE is established in the main clutch 3.

The above pair is higher than i_y/i_xAn important advantage of the method of performing a positive torque upshift in gear ratio is that the first electric motor 4a ensures that the input shaft 1 is synchronized much faster than is possible using only an ICE, since the ICE has a large moment of inertia and changing its rotational speed is slow. Thus, the powertrain of the present invention can provide very fast shifts, since a higher gear can be engaged before the ICE reaches the lower rotational speed of the synchronizing input shaft 1.

Torque levels during gear shifts are improved by optimized use of the first and second electric motors. Typical full throttle under gear ratio i in the lower gear_y/i_x。

The first motor 4a and the second motor 4b can be increased to a torque level significantly higher than the continuous power output in a short period of time (sec/min). The increased power is typically much longer than the time available for shifting.

The kinetic energy connected to the first motor 4a and the second motor 4b can only provide an effect in a very short period of time. However, the time required to disengage/engage a gear is typically about 100ms, and kinetic energy can therefore provide a beneficial effect during a gear shift.

Description of positive torque upshift control strategy targeting maximum torque and short shift time:

2. Torque is transmitted to the driven wheels 8 by engaging the slipping second clutch 5 b. To achieve the maximum torque at the output shaft 6, both the first electric motor 4a and the second electric motor 4b operate as motors (i.e., generate torque from the electric power supplied from the battery pack), and supply the maximum positive torque to the second clutch 5 b.

3. The torque in the first clutch 5a is controlled to be equal to the combined torque in the first electric motor 4a and the main clutch 3. The main clutch 3 will be controlled to have a small and limited speed difference.

4. The low gear is disengaged while using the rotational kinetic energy connected to the second electric motor to provide maximum torque to the output shaft 6.

5. The speed of the input shaft 1 is reduced by the torque in the first clutch 5a being higher than the combined torque in the first electric motor 4a and the main clutch 3. The main clutch 3 is slipping and in this way the fastest possible shift time is achieved. At this point, the kinetic energy connected to the first electric motor 4a and the input shaft 1/main clutch 3 can be used to increase the speed of the second electric motor 4b again (this is done in order to make it possible to use the rotational kinetic energy when a new gear is to be engaged).

6. When the speed of the input shaft 1 is synchronized with the new higher gear and the torque in the first clutch 5a is controlled to be equal to the torque in 4a +3, the new higher gear is engaged while using the rotational kinetic energy connected to the second electric motor 4b to provide the maximum torque to the output shaft 6.

7. The full torque from the ICE is built up in the main clutch 3 without any slip in the main clutch 3.

Positive torque downshift (e.g. kick-down)

A positive torque downshift is one of the most challenging shifts for all types of transmissions. The reason for this is that the ICE (or electric motor) will need to accelerate to a higher rotational speed and it will take time before torque is available at the new higher rotational speed. Two different driving situations where this is an important performance are:

a) full throttle on an uphill grade and insufficient power to maintain speed. Fast downshifts and torque filling will be important to keep the speed as fast as possible.

b) Another situation is what is commonly referred to as a forced downshift. This means that the throttle is fully open to provide rapid acceleration. Fast downshifts and torque filling will be important to keep the latency of the new higher torque as low as possible.

Positive torque downshift control strategy:

2. The main clutch 3 is disengaged as quickly as possible to start the acceleration of the ICE.

3. Torque is transmitted to the driven wheels through the second motor 4b and the second clutch 5b that engages slipping.

4. The combined torque of the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque of the main clutch 3 (the first clutch 5a is at least slipping).

Steps

2, 3 and 4 occur simultaneously.

5. Once step 4 is established, the low gear is disengaged.

6. The first electric motor 4a provides the maximum increased torque to accelerate the speed of the input shaft 1 to the speed of the low gear. (Note that the first electric motor 4a will be able to accelerate faster than the ICE, and the input shaft 1 will achieve the correct speed for the low gear before the ICE, so that engagement of the low gear can begin or complete before acceleration of the ICE is complete)

7. When the speed of the input shaft 1 is synchronized with the new low gear and the combined torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3, the new low gear is engaged.

8. The full torque from the ICE is established in the main clutch 3.

The control strategy will also vary depending on the percentage of torque requested by the driver/cruise control or other input. If only a small increase in torque on the output shaft 6 is required, it will generally be possible to use slightly more of the available torque from the ICE, the first electric motor 4a and the second electric motor 4b to produce a higher torque charge.

V. the first electric motor 4a and the second electric motor 4b function as a starter and an alternator of the ICE.

The use of electric motors as alternators and starters in hybrid systems is not new. The motivation for using these motors would be to save the cost of a standard alternator and starter. The main challenge generally associated with the starter function is to achieve this in all driving situations.

One advantage of the state of the art control software of the transmission or powertrain is that the system will be able to anticipate to a large extent what the next second will require in terms of torque required. This will also make it easier to start the ICE at the correct time.

The powertrain of the present invention will have an easier job to handle what would be a typical start of an ICE than prior art solutions, for example when the vehicle is already running at low torque and it is desired to start the ICE. In many such situations, it will be sufficient to engage the second electric motor 4b and the second clutch 5b to continue to provide torque at the output shaft 6 while the first electric motor 4a and the first clutch 5a start the ICE. It is also possible to use the rotational kinetic energy in the first electric motor 4a and the input shaft 1 to start the ICE.

The most challenging situation to expect is when the vehicle is traveling in a lower gear in electric mode. At this time, the second motor 4b and the second clutch 5b will not be able to provide a significant torque at the output shaft 6 because of the gear i connecting the second motor 5b_yThe transmission ratio will be in the higher gear.

Then the following control strategy for ICE start-up would be clearly advantageous when driving in a lower gear:

1. the first electric motor 4a and the second electric motor 4b operate in rotational engagement with the input shaft 1 of the transmission 2. The first clutch 5a is closed (engaged), and the second clutch 5b and the main clutch 3 are opened (disengaged).

2. The system detects that an ICE boot is requested.

3. The first clutch 5a starts to disengage.

4. Once the first clutch 5a starts to slip, the second electric motor 4b starts a boost mode (peak torque) to accelerate the rotation speed toward the maximum rotation speed. This feature prevents excessive wear of the clutch and provides maximum effect from the motor.

5. During disengagement of the first clutch 5a, the boost mode of the first electric motor 4a will compensate for the reduced torque from the first clutch 5a to the input shaft 1.

6. When the available rotational kinetic energy of the second electric motor 4b and the increased torque are sufficient to start the ICE, the first clutch 5a and the main clutch 3 will be engaged simultaneously, so that the sum of the torques at the input shaft 1 will be zero. Therefore, in the first clutch 5a × i_xThe additional torque applied will be the same as the torque used to start the ICE with the main clutch 3 engaged.

The rapid changes in torque possible in the first and second

electric motors

4a, 4b makes it possible to filter the reaction at the input shaft 1 when the ICE is fired.

Avoid shifting at ICE before top of hill-running in two different gears with electric motor. In this case, the boost mode may also be very supportive.

Prior art software for deciding when to change gear in the most fuel efficient way in modern commercial trucks comprises an overview of the height profile of the road ahead, speed limits etc. This includes the ability to avoid unnecessary shifts, e.g., as before the top of a hill is reached. This has proven to significantly reduce fuel consumption.

A very typical driving situation is when the vehicle is driving in one of the highest gears and uphill before the top of the hill. The most fuel efficient drive would be to use the first and second motors at their peak power to reach the top of the hill at the desired speed. This may be achieved by the power system of the present invention by the following method/process:

1. the first electric motor 4a and the second electric motor 4b operate in rotational engagement with the input shaft 1 of the transmission 2. The first clutch 5a is closed (engaged), and the second clutch 5b is opened (disengaged). The ICE operates with the main clutch 3 closed.

Once the system detects that more torque is required, but only for a short time:

2. the first electric motor 4a provides its maximum torque.

3. The first clutch 5a starts to disengage.

4. When the first clutch 5a starts to slip, the second electric motor 4b starts a supercharging mode (peak torque) to accelerate the rotation speed.

5. When the second motor reaches the correct rotational speed, the second clutch 5b starts to be engaged.

6. Steps 4 and 5 continue until the first clutch 5a is fully open and the second clutch 5b is fully closed.

This method/process will be used in the case where the ICE is running with the main clutch 3 engaged and the second electric motor 4b is able to provide a higher torque to the output shaft 6 on the second clutch 5b than on the first clutch 5 a. This will normally be the case in higher gears, but since most of the driving takes place in higher gears, this will be a very common and usual method/procedure.

Changing the load from a road or traffic slow acceleration/deceleration

Furthermore, when driving in an electric-only mode, it is important to improve efficiency as much as possible, as this gives a longer electrical range, and an alternative is to invest in a larger battery pack. The electric-only mode will be used at least when the torque demand is low for a period of time. This may be in slow moving traffic, slow acceleration, deceleration or in relatively flat but less inclined uphill or downhill roads. This strategy is particularly useful at low and medium speeds.

In this case, it will generally be optimal for the first electric motor 4a to run on the input shaft 1 and for the second electric motor 4b to run in rotational engagement with the output shaft 6 (second clutch 5b closed). For example, the first electric motor 4a may be operated in the gear that gives the highest possible mechanical output without any shifting action delaying the torque response. At the same time, the second electric motor 4b can be operatively connected to the output shaft 6 at a much lower rotational speed, thereby providing very good efficiency for low torque driving situations. This has proven to be a very effective strategy for electric vehicles that use one motor for the front wheels and one motor for the rear wheels. This is now achieved in conjunction with the transmission 2 by the powertrain of the present invention.

VIII negative torque downshift

Description of negative torque downshift control method/procedure:

1. the first electric motor 4a and the second electric motor 4b operate in rotational engagement with the input shaft 1 of the transmission 2. The first clutch 5a is closed (engaged), and the second clutch 5b is opened (disengaged).

2. The torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3. At least the first clutch 5a is slipping. Torque is transmitted to the driven wheels 8 by engaging the slipping second clutch 5 b.

3. Disengaging the high gear.

4. The speed of the input shaft 1 is increased by the torque in the first electric motor 4a and the first clutch 5a being higher than the torque in the main clutch 3. The main clutch 3 is slipping. It should be noted that the powertrain of the present invention has a significant advantageous effect in that the second electric motor 4b can provide a negative torque at the output shaft 6, while the first electric motor 4a can accelerate the input shaft 1 quickly to the desired speed and in this way shift gears as fast as possible.

5. When the speed of the input shaft 1 is synchronized with the new lower gear and the torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3, the new lower gear is engaged.

6. A target negative torque from the ICE is established in the main clutch 3.

IX. negative torque upshift

Description of negative torque upshift control method/procedure:

3. Disengaging the low gear.

4. The speed of the input shaft 1 is reduced by the torque in the first electric motor 4a and the first clutch 5a being higher than the torque in the main clutch 3. It should be noted that the powertrain of the present invention has a significant advantageous effect in that the second electric motor 4b can provide a negative torque at the output shaft 6, while the first electric motor can rapidly decelerate the input shaft 1 to a desired speed and in this way shift gears as fast as possible.

5. The new higher gear is engaged when the speed of the input shaft 1 is synchronized with the new higher gear and the torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the main clutch 3.

6. A target negative torque from the ICE is established in the main clutch 3.

Based on the above disclosure, it is apparent that the power system of the present invention provides a number of advantageous effects.

Although the above methods/processes are described using the power system of the present invention featuring an ICE, it should be noted that many of the above methods and their advantages also apply to embodiments of the power system of the present invention that do not have an ICE. The above-mentioned positive torque upshift I may be performed, for example, by:

1. the first motor 4a and the second motor 4b operate in rotational engagement with the input shaft 1 of the gearbox 2. The first clutch 5a is closed and the second clutch 5b is open.

2. The torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the input shaft 1. (at least the first clutch 5a is slipping). Torque is transmitted to the driven wheels 8 (via the output shaft 6) by engaging the slipping second clutch 5 b. It should be noted that the torque in the second clutch 5b will normally be higher than the torque in the first clutch 5a due to the torque from the second electric motor 4b, and the kinetic energy in the second electric motor 4b is used when braking the second electric motor 4b in speed.

3. Disengaging the low gear.

4. Since the torque in the first electric motor 4a and the first clutch 5a is higher than the torque in the input shaft 1, the rotation speed of the input shaft 1 is reduced.

5. Step 6 may be performed when the rotational speed of the input shaft 1 is synchronized with the new higher gear and the torque in the first electric motor 4a and the first clutch 5a is controlled to be equal to the torque in the input shaft 1.

6. The new higher gear is engaged. It should be noted that the torque in the second clutch 5b is generally higher than the torque in the first clutch 5a because the torque from the second electric motor 4b and the kinetic energy in the second electric motor 4b are used when braking the second electric motor 4b in speed.

Claims

1. A power system includes a transmission (2), a first electric motor (4a), and a second electric motor (4b), wherein,

-the transmission comprises: an input shaft (1) to which a mechanical power source is connectable; an output shaft (6); and a gear assembly providing at least two different transmission ratios which can be selected for transmitting mechanical power from the input shaft (1) to the output shaft (6),

-the first electric motor (4a) is connected to the input shaft (1) such that torque and rotational energy are transmitted between the first electric motor and the input shaft, and

-the second electric motor (4b) is connected to the input shaft (1) via a first clutch (5a) such that torque and rotation can be transmitted between the second electric motor (4b) and the input shaft (1), and the second electric motor is connected to the output shaft (6) via a second clutch (5b) such that torque and rotation can be transmitted between the second electric motor (4b) and the output shaft (6), wherein,

the first electric motor (4a) is connected to the second electric motor (4b) via the first clutch (5 a).

2. A powertrain according to claim 1, wherein the first electric motor (4a), the second electric motor (4b), the first clutch (5a) and the second clutch (5b) form part of a torque transmission path bypassing at least two different gears, the torque transmission path being arranged to transmit torque from the input shaft (1) to the output shaft (6) during a gear shift.

3. A power system according to any one of the preceding claims, wherein the first electric motor (4a) is electrically connected to the second electric motor (4b) such that it generates electric power from the torque at the input shaft (1) and transfers the generated electric power to the second electric motor (4 b).

4. A power system according to any one of the preceding claims, wherein the mechanical power source is an Internal Combustion Engine (ICE) or at least one electric motor (4a, 4 b).

5. A power system according to any one of the foregoing claims, in which the mechanical power source is an Internal Combustion Engine (ICE) connected to the input shaft (1) via a main clutch (3).

6. A power system according to any one of the preceding claims, wherein the transmission (2) comprises a countershaft (7) and either one of the first and second electric motors (4a, 4b) is connected to either one of the input and output shafts (1, 6) via the countershaft (7).

7. A power system according to any one of the foregoing claims, wherein any one of the first electric motor (4a) and the second electric motor (4b) is connected to the input shaft (1) or the output shaft (6) via a gear (9, 10, 11) in the transmission (2).

8. A vehicle comprising a powertrain as claimed in any preceding claim.

9. A method of performing a shift from low gear to high gear in a powertrain according to claims 1 and 5, comprising the steps of:

a. -controlling the torque in the first electric motor (4a) and the first clutch (5a) to be equal to the torque in the main clutch (3).

b. Transmitting torque to the output shaft (6) by engaging the second clutch (5 b);

c. disengaging the low gear;

d. -reducing the rotational speed of the input shaft (1) by making the torque in the first electric motor (4a) and the first clutch (5a) higher than the torque in the main clutch (3); and

e. -engaging the high gear when the rotational speed of the input shaft (1) is synchronized with the high gear and the torque in the first electric motor (4a) and the first clutch (5a) is equal to the torque in the main clutch.

10. The method of claim 9, comprising the steps of: after engaging the high gear, a desired torque is established in the input shaft by any combination of the first electric motor, the second electric motor, and the ICE.

11. A method according to claim 10, wherein the required torque is obtained by establishing the total torque from the ICE in the main clutch (3).

12. A method according to any one of claims 9-11, wherein step a is preceded by the step of operating first and second electric motors (4a, 4b) in rotational engagement with the input shaft (1) of the transmission (2), wherein the first clutch (5a) is closed and the second clutch (5b) is open.

13. A method of performing a shift from low to high gear in a powertrain according to any of claims 1-7, comprising the steps of:

a. controlling the torque in the first motor (4a) and the first clutch (5a) to be equal to the torque in the input shaft (1);

c. disengaging the low gear;

d. -reducing the rotational speed of the input shaft (1) by making the torque in the first electric motor (4a) and the first clutch (5a) higher than the torque in the input shaft (1); and

e. -engaging the high gear when the rotational speed of the input shaft (1) is synchronized with the high gear and the torque in the first electric motor (4a) and the first clutch (5a) is equal to the torque in the input shaft (1).

14. The method of claim 13, comprising the steps of: disengaging the second clutch (5b) and transmitting torque from the second electric motor (4b) to the input shaft (1) after the step of engaging the high gear.

15. A method according to claim 13 or 14, wherein step a is preceded by the step of operating the first and second electric motors (4a, 4b) in rotational engagement with the input shaft (1) of the transmission (2), wherein the first clutch (5a) is closed and the second clutch (5b) is open.

16. A method of performing a shift from high gear to low gear in a powertrain according to claims 1 and 5, comprising the steps of:

a. -controlling the torque in the first electric motor (4a) and the first clutch (5a) to be equal to the torque in the main clutch (3);

c. disengaging the high gear;

d. -increasing the rotational speed of the input shaft (1) by making the torque in the first electric motor (4a) and the first clutch (5a) higher than the torque in the main clutch (3); and

17. The method of claim 16, comprising the steps of: after engaging the low gear, a desired torque is established in the input shaft by any combination of the first electric motor, the second electric motor, and the ICE.

18. A method according to claim 17, wherein the required torque is obtained by establishing the total torque from the ICE in the main clutch (3).

19. A method according to any one of claims 16-18, wherein step a is preceded by the step of operating the first and second electric motors (4a, 4b) in rotational engagement with the input shaft (1) of the transmission (2), wherein the first clutch (5a) is closed and the second clutch (5b) is open.

20. A method of performing a shift from high gear to low gear in a powertrain according to any one of claims 1 to 7, comprising the steps of:

c. disengaging the high gear;

d. -increasing the rotational speed of the input shaft (1) by making the torque in the first electric motor (4a) and the first clutch (5a) higher than the torque in the input shaft (1); and

e. the low gear is engaged when the rotational speed of the input shaft (1) is synchronized with the low gear and the torque in the first electric motor (4a) and the first clutch (5a) is controlled to be equal to the torque in the input shaft (1).

21. The method of claim 20, comprising the steps of: after the step of engaging the low gear, disengaging the second clutch (5b) and transmitting torque from the second electric motor (4b) to the input shaft (1).

22. A method according to claim 20 or 21, wherein step a is preceded by the step of operating the first and second electric motors (4a, 4b) in rotational engagement with the input shaft (1) of the transmission (2), wherein the first clutch (5a) is closed and the second clutch (5b) is open.